A SEMINAR PAPER

ON
IMPACT OF SEED PRIMING ON IMPROVING GROWTH,
DEVELOPMENT AND YIELD OF PLANTS UNDER SALT
STRESS CONDITION

Submitted By:

A.B.M. Zahurul Islam

Supervisor:
Reg. No.: 13-05645
Anisur Rahman, PhD
Session: 2019-20 Associate Professor
Department of Agronomy
Group-k

Supervisor:

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 CONTENTS

Sl.
Heading Page No.
No.

01 Abstract 02

02 Introduction 03-06

03 Materials & Method 06

04 Results & Discussion 07-12

05 Conclusion 13

06 Recommendation 13

07 References 14-15

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Impact of Seed Priming on Improving Growth, Development and
Yield of Plants Under Salt Stress Condition
by

A.B.M. Zahurul Islam

ABSTRACT

Salinity is one of the major abiotic stresses that affect crop production in arid and semiarid
areas. Seed germination and seedling growth are the stages most sensitive to salinity. Salt
stress causes adverse physiological and biochemical changes in germinating seeds. It can
affect the seed germination and stand establishment through osmotic stress, ion-specific
effects and oxidative stress. Various techniques can improve emergence and stand
establishment under salt conditions. One of the most frequently utilized is seed priming. Seed
priming is a pre-sowing treatment which leads to a physiological state that enables seed to
germinate more efficiently. Seed priming stimulates the pre-germination metabolic processes
and makes the seed ready for radicle protrusion. It increases the antioxidant system activity
and the repair of membranes. These changes promote seed vigor during germination and
emergence under salinity stress. Seed priming treatment had better growth performance
through accumulation of soluble sugar and free proline contents, enhancing the activities of
superoxide dismutase (SOD) and catalase (CAT). As seed priming has great effect on
germination and seedling establishment and growth, it ultimately increases the yield of crops.
Various studies confirmed that seed priming has several advantages including, early
emergence high water use efficiency, stand establishment, deeper roots germination in broad
range of temperature and resistance against disease and environmental stresses like drought,
salinity etc. Seed priming has great effect to ameliorate the effect of salt stress in plants and it
increases the germination rate, growth and yield of plants.

1
A seminar paper presented by A.B.M. Zahurul Islam on 06 September, 2020 for the partial
fulfillment of MS degree
2
An MS student in the Department of Agronomy, Sher-e-Bangla Agricultural University,
Dhaka-1207.

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 INTRODUCTION

Salinity in soil or water is one of the major abiotic stresses. It is most widespread in arid,
semiarid and coastal regions. Salinization spreads more in irrigated lands. This is owing to
inappropriate management of irrigation and drainage, low precipitation, high evaporation and
irrigation with saline waters (Munns and Tester, 2008). The soil of 34 million hectares of
irrigated land are salt-affected worldwide. Waterlogging and related salinity affect 60-80
million hectares (FAO, 2011). High salinity levels take 1.5 million hectares of land out of
production each year (Pitman and Läuchli, 2002; Munns and Tester, 2008). Thus, 50% of
cultivable lands will be lost by the middle of the 21st century (Wang et al., 2003). Most crops
are highly susceptible to saline soil, even when sail has electrical conductivity (ECe) as low
as 3 dS m-1. Thus, salinity stress appears to be a major constraint to the productivity of crops
(Shannon, 1997; Xu et al., 2000; Kaya et al., 2003). Seed germination and seedling growth
are the two critical stages for the establishment of crops (Hubbard et al., 2012). These stages
are the most sensitive to abiotic stress (Patade et al., 2011). Germination of high quality seeds
may be delayed or prevented by various abiotic stresses (Jamil et al., 2005; Fazlali et al.,
2013). Läuchli and Grattan (2007) proposed a generalized relationship between germination
percentage and time of germination after adding water at different salt levels. Generally, low
salt concentration induces a state of dormancy and decreases the germination rate.
Meanwhile, 5 high salt concentration inhibits the seed germination and decreases the
germination percentage (Shannon and Grieve, 1999; Khan and Weber, 2008).

The germination of most crops fails on saline soils. This is often a result of high salt
concentrations in the seed planting zone. High quality seeds play an important role in
successful crop production. Rapid germination and emergences are essential for successful
crop establishment, for which seed priming could play an important role. Seed Priming is a
process which increases the germination percentage and reduces the time of emergence;
because the primed seeds of plants completed their chitting period (seed absorb maximum
water and complete all processes before germination during priming). During priming
process, seeds are soaked in different solutions with high osmotic potential. Different type of
solutions according to the seed requirement was used for seed priming. The purpose of
soaking of seed in the solution is to prevent the enough water absorption for radical

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emergence and expand the seed in lag phase. Seed priming protects the disease attack by
applying the coating of fungicides, bactericides and nematicides. Seed priming is used to
increase the germination percentage and seed vigor (Nawaz et al., 2013). Primed seeds have
great potential to grow under stressful conditions. It has strong resistance against disease and
insect attack.

Salinity has several unfavorable effects on plant growth owing to low soil osmotic stress,
ionic imbalances, or combined effects of these factors (Ashraf 2004). All these variables
affect plant growth and development with adverse physiological and biochemical impacts
(Munns and James 2003). The plant’s development or survival is evaluated by integrating
many physiological processes that happen within the plant to assess the salinity stress
tolerance of the plant.Primed seeds have much growth potential and give more production as
compared to non-primed seeds.

It is well established in the literature that salinity causes severe decrease in plant yield.
Several studies have already determined the fact that crops are adversely affected by this
phenomenon, from planting to harvesting and even in storage. Salinity not only adversely
affects seed yield and yield components in many plant species such as lupine (Dawood et al.
2016), common bean (Rady et al. 2016a), wheat (Ouda et al. 2015; Rady et al. 2016a), and
faba bean (Orabi and Abdelhamid 2016) but also causes a nutritional imbalance in seed
quality in terms of decreasing oil percentage, carbohydrates, and concentrations of 17 amino
acids in lupine seeds (Dawood et al. 2016) and decreasing protein content in leaves and oat
grains, with increasing level of salt in irrigation water (Kumar et al. 2010). In contrast, in
saline condition primed seeds raised carbohydrate and protein in seed yield of two faba bean
cultivars (Orabi and Abdelhamid 2016) and increased protein, phenolic concentration, and
lupine seed alkaloids (Dawood et al. 2016). It showed that more yield and uniformity as
compare to non-primed seeds.

Seed priming is a pre-sowing strategy for influencing seedling development by modulating

pre-germination metabolic activity prior to emergence of the radicle and generally enhances
rapid, uniform emergence and plant performance to achieve high vigor and better yields
(McDonald, 2000). During priming, seeds are soaked in different solutions with high osmotic
potential so that pre-germinative metabolic activities proceed, while radicle protrusion is
prevented and then seeds are dried back to the original moisture level.

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Hussain, I. et al (2013). used different terms depending upon the method adopted for priming,
namely;

Hydropriming is the simplest method of seed priming, which relies on seed soaking in pure
water and re-drying to original moisture content prior to sowing. Hydro-priming plays an
important role in the seed germination, radical and plumule emergence in different crop
species under saline and non-saline conditions and also have beneficial effect on enzyme
activity required for rapid germination. Beneficial effect of hydropriming on seed
germination and seedling growth under both optimal and stress conditions, in various crop
plants such as chickpea, maize, rice, mungbean and capsicum has been observed. Caseiro et
al., (2004) found that hydro-priming was the most effective method for improving seed
germination of onion, especially when the seeds were hydrated for 96 hr compared to 48 hr.

Osmo-priming technique refers to soaking of seeds for a certain period in solution of sugar,
PEG etc followed by air drying before sowing. Osmo-priming not only improves seed
germination but also enhance crop performance under non saline or saline conditions.
Salehzade et al., (2009). conducted a study to enhance germination and seedling growth of
wheat seeds using osmo-priming treatments. Seeds were osmo-primed with PEG-8000
solution for 12 hours. Osmo-priming treatments improved the seedling stand establishment
parameters.

Halo-priming refers to soaking of seeds in solution of inorganic salts i.e., NaCl, KNO3,
CaCl2 and CaSO4 etc. Priming with NaCl and KCl was helpful in removing the deleterious
effects of salts (Iqbal et al., 2006). In sorghum seeds soaked in CaCl2 or KNO3 solution
increased the activity of total amylase and proteases in germinating seeds under salt stress
(Kadiri and Hussaini, 1999).

Biopriming involves seed imbibition together with bacterial inoculation of seed (Khan AA
,1992). As other priming method, this treatment increases rate and uniformity of germination,
but additionally protects seeds against the soil and seed-borne pathogens. It was found that

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biopriming is a much more effective approach to disease management than other techniques
such as pelleting and film coating (Basra SMA et al.,2005). Nowadays, the use of biopriming
with plant growth-promoting bacteria (PGPB) as an integral component of agricultural
practices (Golezani, K. G., et al. 2011).

Solid matrix priming (SMP, matriconditioning), in which water uptake by seeds is controlled.
During solid matrix priming, seeds are mixed and incubated with wet solid water carrier for a
certain period. Afterward, seeds are separated from matrix, rinsed, and back-dried. The use of
solid medium allows seeds to hydrate slowly and simulates natural imbibition process
occurring in the soil (McDonald, 2000).

Objectives

However, the present study was conducted with the view of following objectives-

 To observe the effect of seed priming on growth, development and yield of

different plants under salt stress condition.
 To understand the performance of standardized seed priming technique.

MATERIALS AND METHOD

 The seminar paper is exclusively a review paper. This was prepared by collecting data
from secondary sources. Reviewed thesis, journals, publications and books in the
library of SAU, BAU, BSMRAU, BARC, SAIC, BARI, BRRI and Internet for related
data.

 After the collection of necessary data from the above mentioned sources, compilation
was done carefully and arranged systematically for presentation.

 Tables and graphs were added where necessary for clear understanding of the seminar
paper. In some places, only results were shown in the table in a concise form to
present the overall theme in a short cut manner.

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 RESULTS & DISCUSSION

It has also been previously documented that plants are constructing many physiological and
biochemical adaptations to adjust themselves under saline environments. With regard to using
seed priming to alleviate the salt stress effects on plants, we proposed a schematic diagram
describing the chain reaction following the seed priming (Fig. 1). The diagram illustrates the
possible impact of the seed priming on different physiological processes, enhancing tolerance
level and final yield.

Fig 1: Schematic diagram describing the chain reaction following the seed priming.

The salinity can prevent or delay seed germination through various factors, such as the
reduction of water availability, changes in the mobilization of stored reserves and affecting
the structural organization of proteins (Keshavarzi 2012; Sharma et al. 2014; Ibrarim 2016).
According to the results, unprimed seeds submitted to salt stress exhibited increased GRI and
MGT (Fig. 1b and c). Although, when seed priming management was adopted, the seeds did
not show reduction in GRI and MGT parameters, being similar to non-salt stress condition.

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Fig 2: (a) Germination, (b) germination rate index (GRI) and (c) mean germination time
(MGT) in lettuce seeds. Different lowercase letters above the bars indicate significant
differences among Si concentrations within each NaCl concentrations and different capital
letters indicate significant differences of Si concentrations among NaCl concentrations,
according to the Tukey’s test (α = 0.05).

The Effect of Priming and NaCl Concentration. Priming seed with PEG6000 at −1MPa
significantly increased the attributes of germination compared with normal seed (Table 1) and
increasing NaCl concentration significantly reduced the attributes of germination compared
with control treatment (0 NaCl).
Table 1: Means comparison of the effect of priming and NaCl concentration on attributes of
germination.

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Priming seed improved germination at all of NaCl concentration levels compared with
normal seed (Figure 3) and showed that the pattern of response to NaCl concentrations were
the same for normal and primed seed. The primed seed gave both faster germination (FG,
CVG, GRI, and MGT) and led to higher germination (LG) when under salt stress (Figure 3).
Increasing salt stress reduced the speed of germination and the germination rate. For normal
seed this was evident at 50mM NaCl and got progressively worse at each increment of salt
applied (Figure 3).

Fig 3: Germination of Primed seed with PEG6000 at −1MPa (dotted lines) and normal seed
(solid lines).

Under control conditions, primed and nonprimed seedlings looked similar, and no differences
in dry weight, chlorophyll and carotenoid contents were observed (Table 2). Sodium chloride
treatment reduced leaf DW in all plants derived from primed (Pr) and nonprimed (NP) seeds.
Furthermore, leaf DW reduced by 46%, 24%, 26% and 42% in NP, hydroprimed (HP),
hormonal primed (GA3P), and osmoprimed (KNO3P), respectively, under 100 mM NaCl. At
the highest NaCl concentration (200 mM), leaf DW was reduced by 67%, 42%, 61%, and
61%, respectively, under the same condition. This reduction may be explained by the leaf
number and leaf area reductions (Table 2). This result suggests that HP alleviates the effect of
salt on lettuce growth under both NaCl concentrations. Leaf water content was significantly

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reduced under 200 mM NaCl treatment (Table 2), suggesting tissue dehydration occurred
following exposure to severe high NaCl, except for leaf water content of plants derived from
HP seeds.

TABLE 2: Growth (per plant), water content, total chlorophyll (mg −1 chl g−1 FW tissue),
and carotenoids contents (μg g−1 FW tissue) of NP, HP, GA3P and KNO3P lettuce seedlings
grown in the presence of 0, 100 and 200 mM NaCl for 15 d (mean ± SE).

The leaf concentrations of chlorophyll a, chlorophyll b, carotenoids and total pigment in

soybean seedlings from HP and CP under soda saline-alkali stress were significantly
increased compared to UP (Figure 4).

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Fig 4. Effect of unpriming control (UP), hydro-priming (HP) and comprehensive seed
priming (CP) on chlorophyll a, chlorophyll b, carotenoids and total pigment content of
soybean seedlings under soda saline-alkali stress.

The data on plant height of tomato plant as influenced by different seed priming treatments
was presented in the Table 3. Significant variation in the plant height was noticed at 90 DAT
among different varieties and seed priming treatments under saline condition. As influenced
by different priming treatments a mean plant height (cm) has shown in the (Table 3) at 90
DAT. It was highest (150.10cm) from NaCl seed priming (50mM) treatment and lowest plant
height (82.44 cm) was recorded from control under saline condition (Table 3). Number of
branches per plant of tomato was significantly affected by the different seed priming
treatment under saline condition at 90 DAT (Table 3). At 90 DAT, where the highest Number
of branches per plant (18.56) was found from P2 and the lowest value (8.67) was found from
P0. Statistically significant variation was recorded for leaf area due to seed priming treatment
at 30 days after flowering. At flowering stage, the maximum leaf area (332.60 cm 2) was
recorded from P2 while the minimum leaf area (158.40 cm2) was found from P0 (Table 3).
Different seed priming treatment under salt stress significantly in terms of number of flower
cluster per plant of tomato. Data revealed that the highest number of flower cluster per plant
(20.44) was found from P2 while the lowest number (9.78) was recorded from P0 (Table 3).
Significant variation was recorded in terms of number of fruits per plant of tomato due to
different seed priming treatment under salt stress. The highest number of fruits per plant
(48.11) was recorded from P2 whereas the lowest number (22.22) was found from P0 (Table
3).

Table 3. Effect of priming treatments on growth & yield contributing parameters of tomato
under saline condition.

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Significant variation was observed for Chlorophyll content values of tomato plant due to
different seed priming treatment under salt stress. At flowering stage, the highest SPAD
values (47.92) was obtained from P2 whereas the lowest SPAD values (22.56) was found
from P0 (Table 4). Different seed priming treatment significantly varied the vitamin-c in
ripen tomato fruit under saline condition. The maximum Vitamin-C content (18.06 mg/100g)
was found from P2 while the minimum content of Vitamin-C (10.26 mg/100g) was achieved
from P0 (Table 4). It was noticed that from the result of the experiment, different seed
priming treatment significantly varied the carotenoid in ripen tomato fruit under saline
condition. The maximum carotenoid content (5.13 mg/100g) was found from P2 while the
minimum content of carotenoid (2.12 mg/100g) was achieved from P0 (Table 4). This
experiment exhibited distinct variation in proline content in leaves of tomato under salt stress
at different seed priming treatment. Result on changes in proline content have been presented
in (Table 4). Among the different seed priming treatment proline content was highest in P2
(5.45 mg/g) and lowest in P0 (2.11 mg/g) (Table 4).

Table 4. Effect of different priming treatments on fruit quality parameters of tomato under
saline condition.

P0= No priming (Control), P1= Hydropriming (distilled water), P2= NaCl priming (50 mM)
and P3= KNO3 priming (200 mM).

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CONCLUSION

Seed priming has been used to improve germination, reduce seedling emergence time,
improve stand establishment and yield. The beneficial effects of priming have been
demonstrated for many field crops. It is the best solution of germination related problems
especially when crops are grown under unfavorable conditions like salt stress. Many priming
techniques have been evolved which are being utilized in many crops now days. It can
enhance rates and percentage of germination and seedling emergence which ensure proper
stand establishment under a wide range of environmental conditions.

RECOMMENDATIONS

 More research works are needed in this aspect to find out appropriate seed priming
method on different plants.

 More research should be done to improve the seed priming application system by
which increase the yield of different plants.

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